1. Field of the Invention
The invention relates to a magnetic control wheel with a magnetic ring, and more particularly to a magnetic ring whose joint is changed in such a way that the line at the joint meets the end face 211 of the flywheel 21 at a non-right angle. In this way, the magnetic gap and the magnetic field being cut can be protected from direct face-to-face collision that causes vibration.
2. Description of the Related Art
A plurality of fitness apparatuses are fitted with a flywheel for providing an inertia force by rotation that can be utilized either as exercise loading or even as means for adjusting the loading. Accordingly, a magnetic control wheel was developed. As shown in FIG. 1, a magnetic control wheel was developed. As shown in FIG. 1, a magnetic control wheel 11 is fitted to an exercise bike. A magnetic control element 14 with a plurality of magnets 13 is installed to create a magnetic field for applying a certain magnetic resistance to the flywheel.
As shown in FIG. 2, the magnetic control wheel 11 serves as a resistance system for a fitness apparatus. Normally, a so-called magnetic ring 12 having excellent electric or magnetic conductivity is interposed between the flywheel 11 and the magnets 13 for improving the property of the electric or magnetic conductivity.
According to different requirements on material quality and cost, the magnetic ring 12 can be divided into different types. One of them is the permanent magnet type by use of aluminum and copper to be primary material for the magnetic ring. Due to the excellent electric conductivity, eddy current can be created on the surface of the magnetic ring, thereby creating a greater resistance.
Another type is applied to the electromagnetic system brake and hybrid generator that primarily employs silicon steel or steel material with low carbon content to be primary material for the magnetic ring. Due to the excellent magnetic conductivity, the resistance caused by cutting the magnetic field lines can be increased.
In taking easy fabrication and low cost into account, the magnetic ring 12 is formed into a ring shape by stamping a plate. Thereafter, the magnetic ring 12 is mounted on the flywheel 11. According to FIG. 2, the magnetic ring 12 is mounted on the external side of the flywheel 11. As shown in FIG. 3, the magnetic ring 12 is mounted on the internal side of the flywheel 11 in adjustment to the magnets 13 of the internal type magnetic control element 15. As shown in FIG. 4, a magnetic control apparatus 16 for the electromagnetic system brake and the hybrid generator includes an electromagnetic coil 17 applying magnetic resistance to the flywheel 11 and the external type magnetic ring 12.
The above-mentioned configuration of the magnetic rings 12 cannot be completely sealed at the joints as if no joints were present. Meanwhile, the welding material does not correspond to the material of the magnetic ring. Thus, magnetic gaps or areas with different permeability will be created in interaction with the magnetic field. Vibrations will arise when the magnetic gaps or areas with different permeability interact with the magnetic field in operation of the flywheel 11, thereby affecting the performance and the service life of the magnetic control wheel in a negative manner.
At present, most of the lines 121 at the joint of the magnetic ring 12 are designed to be perpendicular to the end face of the flywheel 11. This just corresponds to the distribution of the magnetic field of the magnetic control wheel. In this way, the magnetic gap and the magnetic field to be cut collide to each other in a face-to-face way. In other words, the magnetic gaps are opened to a maximal extent and lie opposite to the magnetic field. The magnetic gaps and the different magnetic permeability will cause a loosening and tightening action on the rotation of the flywheel (because of difference in permeability). Thus, vibration of the flywheel arises. If the magnets are fixed in a loose way, vibration will arise in the areas of the magnets, thereby giving out sound. If the magnets are fixed in a tight way, the flywheel creates vibration. Normally, bearing (not shown) is mounted on the flywheel 11. Therefore, the bearing on the flywheel will be affected by a heavier magnetic force to make noise due to vibration. Accordingly, the service life will be reduced.
Therefore, the magnetic resistance mechanism of the conventional magnetic control wheel still leaves much to be desired and is required for improvement.